H and P MRS Interleaved With High Time Resolution Reveals Closely Matching Creatine CH₂ and PCr Dynamics During Exercise.

The rate of intramuscular phosphocreatine (PCr) depletion and recovery in response to exercise estimated from P MRS is an established measure for oxidative capacity. The creatine CH resonance in H MRS is known to exhibit a similar pattern. So far, repeating the exercise for consecutive H and P experiments posed limitations on the interpretation.

Self-Excited Gravitational Instantons.

We present a novel approach to constructing gravitational instantons based on the observation that the gravitational action of general relativity in its teleparallel formulation can be expressed as a product of the torsion and excitation forms. We introduce a new class of solutions where these two forms are equal, which we term the self-excited instantons, and advocate for their use over the self-dual instantons of Eguchi and Hanson. These new self-excited instantons exhibit striking similarities to BPST instantons in Yang-Mills theory, as their action reduces to a topological Nieh-Yan term, which allows us to identify the axial torsion as a topological current and show that the gravitational action is given by a topological charge.

Balanced Steady-State Free Precession Enables High-Resolution Dynamic 3D Deuterium Metabolic Imaging of the Human Brain at 7T.

Objectives: Deuterium (2H) metabolic imaging (DMI) is an emerging magnetic resonance technique to non-invasively map human brain glucose (Glc) uptake and downstream metabolism following oral or intravenous administration of 2H-labeled Glc. The achievable spatial resolution is limited due to inherently low sensitivity of DMI. This hinders potential clinical translation.

Growth Hormone Promotes Hepatic Triglyceride Export in Humans.

Context: Growth hormone (GH) reduces intrahepatic lipids (IHL) according to investigations in healthy volunteers and patients with acromegaly, a disease characterized by long-term GH excess.

Objective: This study investigated underlying antisteatotic pathways stimulated by short-term modulation of GH action.

Methods: Ten healthy male volunteers (26 ± 5 years, body mass index [BMI] 23 ± 3.

Leptin acutely increases hepatic triglyceride secretion in patients with lipodystrophy.

Background And Aims: Metreleptin ameliorates hepatic steatosis partially independent of its anorexic action. We previously showed that metreleptin increases hepatic very low-density lipoprotein triglycerides (VLDL1-TG) export in rodents and healthy humans requiring intact hepatic autonomic innervation. The primary aim of this study was to investigate whether metreleptin has anti-steatotic properties in patients with lipodystrophy by increasing VLDL1-TG export.

Gender-affirming hormone therapy and its impact on myocardial mass and cardiac function: a prospective magnetic resonance cohort study on transgender men and women.

Objective: Differences in cardiac parameters such as myocardial mass, left ventricular ejection fraction (LVEF), cardiac output, and brain natriuretic peptide (NT-proBNP) levels between cisgender men and women are well established. No evidence exists regarding changes in myocardial mass or cardiac function parameters in transgender individuals undergoing gender-affirming hormone therapy (GAHT).

Design, Setting, Participants, And Main Outcomes: A prospective study enrolling transgender individuals under GAHT (20 individuals assigned female at birth [AFAB] and 15 assigned male at birth [AMAB]) was conducted at the Medical University of Vienna from 2019 to 2022.

Assessment of fetal hepatic lipid content by magnetic resonance imaging and association of results with clinical maternal and fetal parameters.

Purpose: To quantify hepatocellular lipids in the fetal liver, we tested the feasibility of the multiecho mDixon Quant sequence (chemical shift encoded magnetic resonance imaging (MRI)) during clinically routine fetal whole-body MRI and investigated the correlation of hepatocellular lipids with different clinical maternal and fetal parameters.

Methods: The livers of 155 fetuses were prospectively investigated with multiecho CSE-MRI sequences during clinically indicated whole-body MRI, performed between gestational weeks 19 and 38 on a 1.5 Tesla scanner.

Balanced steady state free precession enables high-resolution dynamic 3D Deuterium Metabolic Imaging of the human brain at 7T.

Objectives: Deuterium (H) Metabolic Imaging (DMI) is an emerging magnetic resonance technique to non-invasively map human brain glucose (Glc) uptake and downstream metabolism following oral or intravenous administration of H-labeled Glc. The achievable spatial resolution is limited due to inherently low sensitivity of DMI. This hinders potential clinical translation.

The effects of regular exercise on cognitive and cardiometabolic health in testicular cancer survivors subjected to platinum-based chemotherapy.

Background: Platinum-based chemotherapy provides curative treatment to more than 95% of patients with testicular germ cell tumor but it has negative cardiometabolic and neurological effects. Regular exercise can alleviate late chemotherapy-related toxicities. We examined the impact of a 6-month supervised aerobic-strength training on cognitive and cardiometabolic health and residual level of platinum in cancer survivors.

The effects of gender-affirming hormone therapy on myocardial, hepatic, pancreatic lipid content, body fat distribution and other cardiometabolic risk factors: A magnetic resonance-based study in transgender individuals.

Purpose: We aimed to assess the changes in body fat distribution, intraorgan lipid accumulation, and cardiometabolic risk factors after 6 months of gender-affirming hormone therapy (GAHT) in transgender men (TM) and transgender women (TW).

Methods: Conducted at the Medical University of Vienna between 2019 and 2022, the study included 15 TW and 20 TM. We conducted magnetic resonance imaging and spectroscopy to determine the visceral (VAT) and subcutaneous adipose tissue (SAT) amounts, the VAT/SAT ratio, and the intraorgan lipid content (liver, pancreas, myocardium), bloodwork, and an oral glucose tolerance test at baseline and after 6 months of GAHT.

Diagnostic accuracy of texture analysis applied to T- and T-Relaxation maps for liver fibrosis classification via machine-learning algorithms with liver histology as reference standard.

Objectives: To explore texture analysis' ability on T and T relaxation maps to classify liver fibrosis into no-to-mild liver fibrosis (nmF) versus severe fibrosis (sF) group using machine learning algorithms and histology as reference standard.

Materials And Methods: In this single-center study, patients undergoing 3 T MRI who also had histology examination were retrospectively enrolled. SNAPSHOT-FLASH sequence for T1 mapping, radial turbo-spin-echo sequence for T2 mapping and spin-echo echo-planar-imaging magnetic resonance elastography (MRE) sequences were analyzed.

Concentric Ring Trajectory Sampling With k-Space Reordering Enables Assessment of Tissue-Specific T and T Relaxation for H-Labeled Substrates in the Human Brain at 7 T.

Deuterium metabolic imaging (DMI) is an emerging Magnetic Resonance technique providing valuable insight into the dynamics of cellular glucose (Glc) metabolism of the human brain in vivo using deuterium-labeled (H) glucose as non-invasive tracer. Reliable concentration estimation of H-Glc and downstream synthesized neurotransmitters glutamate + glutamine (Glx) requires accurate knowledge of relaxation times, but so far tissue-specific T and T relaxation times (e.g.

Deuterium Metabolic Imaging Enables the Tracing of Substrate Fluxes Through the Tricarboxylic Acid Cycle in the Liver.

Alterations in tricarboxylic acid (TCA) cycle metabolism are associated with hepatic metabolic disorders. Elevated hepatic acetate concentrations, often attributed to high caloric intake, are recognized as a pivotal factor in the etiology of obesity and metabolic syndrome. Therefore, the assessment of acetate breakdown and TCA cycle activity plays a central role in understanding the impact of diet-induced alterations on liver metabolism.

Sex differences in ectopic lipid deposits and cardiac function across a wide range of glycemic control: a secondary analysis.

Objective: The objective of this study was to identify sex differences in ntrahepatocellular (HCL) and intramyocardial lipids (MYCL) and cardiac function in participants with different grades of glucometabolic impairment and different BMI strata.

Methods: Data from 503 individuals from 17 clinical experimental studies were analyzed. HCL and MYCL were assessed with 3T and 7T scanners by magnetic resonance spectroscopy.

Experimental Broad-Based Curved Sidewall Aneurysms in Rabbits Mimicking Human Carotid Siphon Aneurysms: Proof of Feasibility and Comparability Using Computational Fluid Dynamics.

Background/objective: Broad-based sidewall aneurysms of the carotid artery are primarily treated endovascularly. However, recurrence or rupture after treatment still poses a significant risk. Hence, reliable animal models mimicking this aneurysm type are essential for to evaluate the performance of new advanced endovascular devices.

A PET/MRI study on the effect of obesity and NAFLD on hepatic [F]FDG uptake.

Purpose: The potential limitations of hepatic [F]FDG-PET imaging for individuals with obesity and excessive liver fat (NAFLD) are being investigated. In this study, we aim to determine the reliability of standardized uptake values (SUVs) focusing on adjustment for liver fat content (LFC) derived from DIXON images and the effects of whole-body normalizations.

Methods: Lean and with obesity volunteers who underwent [F]FDG-PET/MRI were reviewed retrospectively.

Evaluation of Hepatic Glucose and Palmitic Acid Metabolism in Rodents on High-Fat Diet Using Deuterium Metabolic Imaging.

Background: One of the main features of several metabolic disorders is dysregulation of hepatic glucose and lipid metabolism. Deuterium metabolic imaging (DMI) allows for assessing the uptake and breakdown of H-labeled substrates, giving specific insight into nutrient processing in healthy and diseased organs. Thus, DMI could be a useful approach for analyzing the differences in liver metabolism of healthy and diseased subjects to gain a deeper understanding of the alterations related to metabolic disorders.

Whole-brain deuterium metabolic imaging via concentric ring trajectory readout enables assessment of regional variations in neuronal glucose metabolism.

Deuterium metabolic imaging (DMI) is an emerging magnetic resonance technique, for non-invasive mapping of human brain glucose metabolism following oral or intravenous administration of deuterium-labeled glucose. Regional differences in glucose metabolism can be observed in various brain pathologies, such as Alzheimer's disease, cancer, epilepsy or schizophrenia, but the achievable spatial resolution of conventional phase-encoded DMI methods is limited due to prolonged acquisition times rendering submilliliter isotropic spatial resolution for dynamic whole brain DMI not feasible. The purpose of this study was to implement non-Cartesian spatial-spectral sampling schemes for whole-brain H FID-MR Spectroscopic Imaging to assess time-resolved metabolic maps with sufficient spatial resolution to reliably detect metabolic differences between healthy gray and white matter regions.

Effects of a 10-Week Exercise and Nutritional Intervention with Variable Dietary Carbohydrates and Glycaemic Indices on Substrate Metabolism, Glycogen Storage, and Endurance Performance in Men: A Randomized Controlled Trial.

Background: Daily nutrition plays an important role in supporting training adaptions and endurance performance. The objective of this 10-week study was to investigate the consequences of varying carbohydrate consumption and the glycaemic index (GI) together with an endurance training regimen on substrate oxidation, muscle energy storage and endurance performance under free-living conditions. Sixty-five moderately trained healthy men (29 ± 4 years; VO peak 55 ± 8 mL min kg) were randomized to one of three different nutritional regimes (LOW-GI: 50-60% CHO with ≥ 65% of these CHO with GI < 50 per day, n = 24; HIGH-GI: 50-60% CHO with ≥ 65% CHO with GI > 70 per day, n = 20; LCHF: ≤ 50 g CHO daily, n = 21).

Correlation between skeletal muscle acetylcarnitine and phosphocreatine metabolism during submaximal exercise and recovery: interleaved H/P MRS 7 T study.

Acetylcarnitine is an essential metabolite for maintaining metabolic flexibility and glucose homeostasis. The in vivo behavior of muscle acetylcarnitine content during exercise has not been shown with magnetic resonance spectroscopy. Therefore, this study aimed to explore the behavior of skeletal muscle acetylcarnitine during rest, plantar flexion exercise, and recovery in the human gastrocnemius muscle under aerobic conditions.

Gpcpd1-GPC metabolic pathway is dysfunctional in aging and its deficiency severely perturbs glucose metabolism.

Skeletal muscle plays a central role in the regulation of systemic metabolism during lifespan. With aging, this function is perturbed, initiating multiple chronic diseases. Our knowledge of mechanisms responsible for this decline is limited.

Effects of gender-affirming hormone therapy on cardiovascular risk factors focusing on glucose metabolism in an Austrian transgender cohort.

Objective: We aimed to investigate the effect of gender-affirming hormone therapy (GAHT) on cardiovascular disease risk factors focusing on glucose tolerance.

Patients And Methods: This primarily translational study enrolled 16 transgender persons assigned female at birth (AFAB), 22 assigned male at birth (AMAB), and 33 age- and BMI-matched cisgender controls at the Medical University of Vienna from 2013 to 2020. A 3-Tesla MRI scan to measure intramyocardial, pancreatic, hepatic fat content and subcutaneous-to-visceral adipose tissue ratio (SAT/VAT-ratio), an oral glucose tolerance test (oGTT), bloodwork including brain natriuretic peptide (pro-BNP), sex hormones and two glucose-metabolism related biomarkers (adiponectin, betatrophin) were performed.

Novel approach using [F]FTHA-PET and de novo synthesized VLDL for assessment of FFA metabolism in a rat model of diet induced NAFLD.

Background And Aims: The worldwide prevalence of Non-alcoholic Fatty Liver Disease (NAFLD) raises concerns about associated risk factors, such as obesity and type 2 Diabetes Mellitus, for leading causes of disability and death. Besides Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS), functional imaging with Positron Emission Tomography (PET) could contribute to a deeper understanding of the pathophysiology of NAFLD. Here we describe a novel approach using the PET tracer [F]FTHA, which is an analog of long-chain free fatty acids (FFA) and is taken up by tissues to enter mitochondria or to be incorporated into complex lipids for further export as very-low-density lipoprotein (VLDL).